Layered reinforced product based on non-woven fabric, particularly for bituminization, and method for producing the product

ABSTRACT

A reinforced layered product based on non-woven fabric, which comprises:  
     at least one first ply of non-woven fabric made of polyester fibers predominantly orientated along a predefined direction;  
     at least one second ply chosen between a non-woven fabric made of polyester fibers that are predominantly orientated at right angles to the at least one first ply and melt at a lower temperature, and a layer of a hot-melt adhesive;  
     at least one third ply of non-woven fabric made of polyester fibers predominantly orientated along the direction of predominant orientation of the at least one first ply;  
     at least one net of glass fibers arranged between two plies having different orientations selected among the at least one first ply, the at least one second ply, and the at least one third ply  
     the fibers of the at least one second ply or of the layer of hot-melt adhesive being bonded by heat with the other plies that are in contact with them, the entire assembly being consolidated by means of resin.

[0001] The present invention relates to a reinforced layered productbased on non-woven fabric.

[0002] The product is used particularly but not exclusively as abituminization mat.

[0003] The present invention also relates to a method for manufacturingthe layered product.

BACKGROUND OF INVENTION

[0004] Mats for bituminization, made of layered non-woven fabric ofpolyester fibers, are already known.

[0005] These mats are generally composed of three plies of non-wovenfabric of polyester fibers, with a melting temperature of approximately255° C., a count of 4.4 dtex and a size of 76 mm, which are superimposedand in which the central ply is formed by a carding machine thatarranges the fibers predominantly longitudinally with respect to thedirection of advancement of production and the external plies areproduced by respective carding machines that arrange the fiberspredominantly in a transverse direction.

[0006] Each ply constitutes, in terms of weight, one third of the totalweight of the assembly.

[0007] The assembly is subjected to consolidation by passing throughthree needle punches arranged in series and is then treated with resinand dried in an oven and finally rolled up in rolls.

[0008] A product of this type weighs no less than 140 g/m², of whichapproximately 20% is constituted by the resin.

[0009] Lower unit weights are not considered, since they would lead togreat shrinkage both during bitumen impregnation and during laying.

[0010] The resin treatment is in fact designed to minimize shrinkage,but can nonetheless be insufficient for this purpose.

[0011] For this reason, and also in view of research into reducing thequantity of resin, which is a very expensive raw material, it is knownto reinforce the non-woven fabric mat with glass fibers embedded invarious manners between the various layers and thus bonded to theassembly.

[0012] The methods used so far have led to improvements, but have notyielded results that can be considered optimum.

SUMMARY OF THE INVENTION

[0013] The aim of the present invention is to provide a reinforcedlayered product based on non-woven fabric that has improved stabilitywith respect to shrinkage in all directions and contains a reducedamount of resin.

[0014] Within this aim, an object of the present invention is to providea reinforced layered product based on non-woven fabric that can beproduced with a method that is advantageous with respect to currentmethods in terms of productivity per hour.

[0015] Another object is to provide a reinforced layered product basedon non-woven fabric that can be produced without particulartechnological complications with respect to known products.

[0016] A further object is to provide a reinforced layered product basedon non-woven fabric whose cost for raw materials is not higher than thatof current products.

[0017] A still further object is to provide a reinforced layered productbased on non-woven fabric that can be produced by using currentfacilities.

[0018] This aim and these and other objects that will become betterapparent hereinafter are achieved by a reinforced layered product basedon non-woven fabric, characterized in that it comprises: p1 at least onefirst ply of non-woven fabric made of polyester fibers predominantlyorientated along a predefined direction;

[0019] at least one second ply chosen between a non-woven fabric made ofpolyester fibers that are predominantly orientated at right angles tosaid at least one first ply and melt at a lower temperature, and a layerof a hot-melt adhesive that melts at a lower temperature;

[0020] at least one third ply of non-woven fabric made of polyesterfibers predominantly orientated along the direction of predominantorientation of said at least one first ply;

[0021] at least one net of glass fibers arranged between two plieshaving different orientations selected among said at least one firstply, said at least one second ply, and said at least one third ply

[0022] the fibers of said at least one first ply and said at least onethird ply being bonded by heat;

[0023] to the fibers of said at least one second ply that are in contactwith them, when said second ply is constituted by a non-woven fabricmade of polyester fibers;

[0024] to said layer of a hot-melt adhesive, when said at least onesecond ply is constituted by said layer of adhesive

[0025] the entire assembly being consolidated by means of resin.

[0026] Advantageously, the method for producing said reinforced layeredproduct based on non-woven fabric with said at least one second plyconstituted by a non-woven fabric made of polyester fibers comprises thesteps of:

[0027] feeding a carding machine that lies transversely to a directionof advancement of the product with said at least one first ply and atleast one third ply of non-woven fabric of polyester fiberspredominantly orientated transversely and a longitudinal carding machinewith said at least one second ply of non-woven fabric of polyesterfibers that have a predominant longitudinal orientation and melt at alower temperature than the preceding ones;

[0028] arranging at least one net of glass fibers at least between oneof said plies with predominant transverse orientation and the ply withpredominant longitudinal orientation;

[0029] calendering the assembly at the temperature at which said atleast one ply with predominant longitudinal orientation softens,consolidating it and bonding said at least one glass fiber net;

[0030] resin-treating the assembly and drying it.

[0031] Equally advantageously, the method for producing said reinforcedlayered product based on non-woven fabric with said at least one secondply constituted by a layer of hot-melt adhesive comprises the steps of:

[0032] feeding a carding machine that lies longitudinally with respectto the advancement direction of the product with said at least one firstply and said at least one third ply made of non-woven fabric ofpolyester fibers with predominant transverse orientation;

[0033] spreading said layer of hot-melt adhesive on the inner side ofone of said at least one first ply and at least one third ply;

[0034] arranging said at least one net of glass fibers between said atleast one first ply and said at least one third ply;

[0035] calendering the assembly at the softening temperature of saidlayer of hot-melt adhesive, consolidating and bonding said at least oneglass fiber net;

[0036] resin-treating the assembly and drying it.

BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Further characteristics and advantages of the present inventionwill become better apparent from the following detailed description of apreferred but not exclusive embodiment thereof and of its productionmethod, given by way of non-limiting example in the accompanyingdrawings, wherein:

[0038]FIG. 1 is a schematic perspective view of a layered productaccording to the invention;

[0039]FIG. 2 is an exploded perspective view of the main components ofthe product of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0040] With reference to the figures, a reinforced layered product basedon non-woven fabric comprises at least one first ply 10 of non-wovenfabric made of polyester fibers with predominant orientation along apredefined direction.

[0041] Preference is given to a ply with a count of 4.4 dtex, a size of76 mm, a weight of 45 g/m², and a melting temperature of approximately255° C.

[0042] The product further comprises at least one second ply 11 chosenbetween a non-woven fabric of polyester fibers that are predominantlyorientated at right angles to said at least one first ply 10 and melt ata lower temperature, and a layer of a hot-melt adhesive that likewisemelts at a lower temperature.

[0043] Preference is given in this case to a ply with a count of 4.4-6.7dtex, a size of 76 mm, a weight of 10 g/m², and a melting temperature ofapproximately 234° C.

[0044] The layer of low-melt adhesive is based on at least one amongpolyester, polyurethane, acrylates and the like.

[0045] The product further comprises at least one third ply 12 ofnon-woven fabric made of polyester fabrics that are predominantlyorientated along the direction of predominant orientation of said atleast one first ply 10 and have the same characteristics as said firstply.

[0046] At least one net 13 of glass fibers weighing approximately 8 g/m²is arranged between two differently orientated plies among said at leastone first ply 10, at least one second ply 11, and at least one third ply12.

[0047] The glass fiber net 13 can have various denier counts and bemanufactured in various manners, but by way of example it is possible touse a net with a warp having a count of 340 dtex and 1.6 filaments percm, and a weft having a count of 340 dtex and 0.4 filaments per cm, theentire system being bonded by polyvinyl alcohol.

[0048] The fibers of the at least one second ply 11 are thermally bondedto the fibers of the other plies 10 and 13 that are in contact withthem, and the entire assembly is resin-treated with resin preferably inan amount of approximately 12 g/m², i.e., approximately 10% of theweight of the assembly.

[0049] The production method of the reinforced layered product based onnon-woven fabric comprises, if the second ply 11 is constituted by anon-woven fabric of polyester fibers, a first step in which a cardingmachine that lies transversely to the direction of advancement of theproduct is fed with the at least one first ply 10 and at least one thirdply 12 of non-woven fabric of polyester fibers having a predominantlytransverse orientation, and a longitudinal carding machine is fed withthe at least one second ply 11 of non-woven fabric of polyester fibersthat have a predominantly longitudinal orientation and melt at a lowertemperature than the preceding plies.

[0050] At the same time, the at least one net 13 of glass fibers isarranged between one of the plies having a predominant transverseorientation 10 and 12 and the ply 11 that has a predominant longitudinalorientation, and the assembly is pre-needle punched enough to allowtransport to a calendering machine that is heated to approximately 210°C., a temperature at which the at least one ply 11 with predominantlongitudinal orientation softens and, by being of the same kind as thefibers that constitute the transverse plies 10 and 12, leads to aconsolidation of the assembly, also bonding the at least one glass fibernet 13.

[0051] If the second ply 11 is constituted by a layer of hot-meltadhesive, which also melts at a lower temperature than the first ply 10and the third ply 12, the production method comprises a first step inwhich a carding machine that lies longitudinally with respect to theproduct advancement direction is fed with the at least one first ply 10and the at least one third ply 12.

[0052] Such layer of hot-melt adhesive is applied to the inner side ofone of the at least one first ply 10 and the at least one third ply 12.

[0053] Such at least one net of glass fibers is then arranged betweenthe at least one first ply 10 and the at least one third ply 12.

[0054] The assembly is calendered at the softening temperature of saidlayer of hot-melt adhesive, consolidating it and bonding said at leastone glass fiber net.

[0055] The resulting intermediate component is therefore athermally-bonded reinforced non-woven fabric, which in the final step ofboth processes is resin-treated, dried in an oven and then rolled intorolls.

[0056] The resin treatment is designed to minimize shrinkage both duringbituminization and during installation.

[0057] The presence of the glass fiber net improves shrinkage stabilityin all directions and leads to a reduced need for resin with respect toknown types (10% of total weight with respect to 20%).

[0058] Consolidation with thermal calendering provides advantages interms of productivity per hour, since it is well-known that thebottleneck of needle-punched non-woven fabrics is constituted by theneedle punches.

[0059] In the present case, only pre-needle punching is performed,exclusively in order to allow transport to the calendering machine.

[0060] In practice it has been found that the present invention hasachieved the intended aim and objects.

[0061] All the technical details may be replaced with other technicallyequivalent elements.

[0062] The materials, so long as they are compatible with the contingentuse, as well as the dimensions, may be any according to requirements.

[0063] The disclosures in Italian Patent Application No. PD2003A000100from which this application claims priority are incorporated herein byreference.

What is claimed is:
 1. A reinforced layered product based on non-wovenfabric, comprising: at least one first ply of non-woven fabric made ofpolyester fibers predominantly orientated along a predefined direction;at least one second ply chosen between a non-woven fabric made ofpolyester fibers that are predominantly orientated at right angles tosaid at least one first ply and melt at a lower temperature, and a layerof a hot-melt adhesive that melts at a lower temperature; at least onethird ply of non-woven fabric made of polyester fibers predominantlyorientated along the direction of predominant orientation of said atleast one first ply; at least one net of glass fibers arranged betweentwo plies having different orientations selected among said at least onefirst ply said at least one second ply, and said at least one third ply,the fibers of said at least one first ply and of said at least one thirdply being bonded by heat to the fibers of said at least one second plythat are in contact with them, when said second ply is constituted by anon-woven fabric made of polyester fibers; to said layer of a hot-meltadhesive, when said at least one second ply is constituted by said layerof adhesive the entire assembly being consolidated by means of resin. 2.The reinforced layered product based on non-woven fabric according toclaim 1, wherein said at least one first ply and said at least one thirdply have substantially a count of 4.4 dtex, a size of 76 mm, a weight of45 g/m², and a melting temperature of approximately 255° C.
 3. Thereinforced layered product based on non-woven fabric according to claim1, wherein said at least one second ply of non-woven fabric made ofpolyester fiber substantially has a count of 4.4-6.7 dtex, a size of 76mm, a weight of 10 g/m², and a melting temperature of approximately 234°C.
 4. The reinforced layered product based on non-woven fabric accordingto claim 1, wherein said layer of a hot-melt adhesive is based on atleast one among polyester, polyurethane, acrylates and the like.
 5. Thereinforced layered product based on non-woven fabric according to claim1, wherein said net of glass fibers has a weight of approximately 8g/m².
 6. The reinforced layered product based on non-woven fabricaccording to claim 1, wherein said glass fiber net has a warp count of340 dtex and 1.6 filaments per cm and a weft count of 340 dtex, and 0.4filaments per cm, the entire system being adhesive-bonded by means ofpolyvinyl alcohol.
 7. The reinforced layered product based on non-wovenfabric according to claim 1, wherein said resin is present in an amountapproximately equal to 10% by weight of the total.
 8. A method forproducing a reinforced layered product based on non-woven fabriccomprising the steps of: feeding a carding machine that is orientatedtransversely to an advancement direction of a product with at least onefirst ply and at least one third ply of non-woven fabric made ofpolyester fibers having a predominant transverse orientation, andfeeding a longitudinal carding machine with at least one second ply ofnon-woven fabric made of polyester fibers that have a predominantlongitudinal orientation and melt at a lower temperature than the firstand third plies; arranging at least one net of glass fibers at leastbetween one of said first and third plies with predominant transverseorientation and the second ply with predominant longitudinalorientation; calendering said first, second, third plies and said atleast one net at a softening temperature of said at least one ply withpredominant longitudinal orientation, consolidating them and bondingthem to said at least one glass fiber net, obtaining an assembly;treating the assembly with resin and drying the assembly.
 9. The methodaccording to claim 8, comprising, before the calendering step, the stepof pre-needle punching the assembly enough to allow transport to thecalendering machine.
 10. The method according to claim 8, whereincalendering is performed at approximately 210° C.
 11. A method forproducing reinforced layered product based on non-woven fabric,comprising the steps of: feeding a carding machine that is orientatedlongitudinally with respect to a direction of advancement of a productwith at least one first ply and with at least one third ply made ofnon-woven fabric made of polyester fibers that have a predominanttransverse orientation; applying a layer of hot-melt adhesive to aninner side of one of said at least one first ply and said at least onethird ply; arranging between said at least one first ply and at leastone third ply at least one glass fiber net; calendering said first,second and third plies and said at least one net at a softeningtemperature of said hot-melt adhesive, consolidating them and bondingsaid at least one glass fiber network, obtaining an assembly;resin-coating the assembly and drying the assembly.
 12. The methodaccording to claim 9, comprising, before the calendering step, the stepof pre-needle punching the assembly enough to allow transport to thecalendering machine.
 13. The method according to claim 9, whereincalendering is performed at approximately 210° C.